Magnetron



July 6, 1948.

R. J. BONDLEY MAGNETRON Filed Dec. 24, 1942 Q r I Inventor- Ralph J.Bondley,

y His Attofney Patented July 6, 1948 MAGNETRON Ralph J. Bondley, Scotia,N. Y., assignor to General Electric Company, a corporation of New YorkApplication December 24, 1942. Serial No. 470,040 4 Claims. (01.250-275) My invention relates to ultra high frequency electric dischargedevices and more particularly to ultra high frequency electric dischargedevices of the magnetron type.

With the ever increasing demand for higher frequencies and because ofthe desirability of using discharge devices of the magnetron type forthis purpose, there has been evidenced a decided need for simplifiedelectrode structure which permits facility in factory production andwhich affords improvements in the operating characteristics of devicesof this type. In accordance with the teachings of my invention describedhereinafter, I provide a new and improved structure for an ultra highfrequency magnetron wherein the anode structure is of simpleconstruction and arrangement and whereby the electrical operatingcharacteristics of the magnetron are substantially improved.

It is an object of my invention to provide a new and improved ultra highfrequency electric discharge device.

It is another object of my invention to provide a new and improved ultrahigh frequency magnetron.

It is a further object of my invention to provide new and improved anodestructure for an ultra high frequency magnetron.

It is a still further object of my invention to provide a new andimproved anode structure for an ultra high frequency magnetron whichdefines a plurality of space resonant regions or cavities, and in whichthe various space resoonant regions are effectively coupled by using asimple arrangement of parts.

Briefly stated, in the illustrated embodiment of my invention I providean ultra high frequency magnetron comprising a centrally locatedcathode, which may be of the thermionic type, substantially surroundedby an annular anode structure. The anode structure comprises an annularmetallic member or ring which supports a plurality of circumferentiallyspaced inwardly extending or radial vanes which may be positioned at oneextremity in slots provided by the ring. The vanes have a substantiallyuniform thickness and are of such number and thickness relative to thediameter of the supporting ring to produce an effective concentration,at their inner extremities, of the electric component of theelectromagnetic oscillations in the various space resonant regionsdefined by adjacent vanes, so that there is an effective interchange ofenergy between the space resonant regions and the oscillating orgyrating electric discharge or space charge of the device. Moreparticularly, the thickness of the vanes is preferably equal to orgreater than the distance between adjacent vanes at the ends facingthecathode so that the electric component of the both, of the radial vanes,and preferably in the plane of the top or bottom of the annular anodestructure.

For a better understanding of my invention,

. reference may be had to the following description taken in connectionwith the accompanying drawing, and its scope will be pointed out in theappended claims. Fig. 1 illustrates an embodimentof my invention asapplied toan ultra high frequency magnetron construction of thetypedisclosed and broadly claimed in a copending patent application SerialNo. 447,903, of Elmer D. McArthur, filed June 22, 1942, and which isassigned to the assignee of the present application and is now UnitedStates Patent No. 2,412,824, issued December 17, 1946. Fig, 2 is a planview of the anode structure.

Referring now to Fig. 1 of the accompanying drawing, my invention isthere illustrated as applied to an ultra high frequency magnetronincluding an elongated cylindrical container, the

lateral wall of which is provided by a single me-.- tallic tube I whichconsists of aferromagnetic material such as cold rolled steel, or thelike. The ends of the container or tube l are closed by flanged members2 and 3 which are welded or otherwise hermetically joined to the innersurface of tube I.

Within the container and approximately at its central region I providean anode structure 4, which is shown in plan view in Fig. 2 and whichcomprises a metallic annular member or ring 5 preferably constructed ofcopper or brass and which is provided with a plurality of annularlyspaced. slots 6 into which are fitted inwardly extending radial-typevanes 'la'lh inclusive, thereby defining a plurality of space resonantregions or cavities which are energized by an oscillating or gyratingspace charge established between the ends of the radial vanes and acathode structure to be described presently.

The diameter of the ring 5, the number of radial vanes and the thicknessthereof are preferably chosen so that. the thickness of the vanes isequalf to or: greaterthan the distance between the inner extremities ofthe vanes facing,-or immediately opposite, the cathode structure. Moreparticularly, referring to Fig. 2, the distance t; is preferably greaterthan the distance d. g

In order to establish a magnetic field, I employ magnetic means whichmay-comprise a'pair of permanently magnetized magnetic pole pieces 8 and9 spaced longitudinally along the axis of the discharge device,and.-.which are respectively seated upon metallic disks Ill and II offerromagnetic material and which in turn areprovided with radiallyextendin passages I2 and I3 :tofiacilitate: extraction. of air or gasduring the evacuation process. 'Passage l3 and the'entire --deviceafterexhaust maybe sealed? bywmeans'of i atmetallic tubulation- Id. attachedto the flanged member 3.

The :anode structure: may be "-firinly ,positioned tbyizmeans' of.a.pair of. annular spacing members 1 l5r'1and l E which abut' the ring5 :andwhich also aarein engagement-with apairof transverse sup portingdisks. lltland l8 which engage suitably formed shoulders provided .bymagnetic pole pieces 8 and 9. Supporting rings l9 and .adapte'dt'to'-beslippedover the pole pieces 8 and 9, 'respectively, may be welded orsoldered to these members'andbasefdisks l0 and II.

'There'.is"provided centrally within the anode t s-tnuc-ture 'ilacathode, such :as a r thermionic cathodegiwhichamay. include :aefiangedt metallic icylirideriZLiLpreferabIy constructedof nickel ormolybdenum, and Which;'is1 coated with: .an electron emissive materialsuch as barium oxide. i'llhere :is also provided a'filamentaryncathode"heating element'i22--.'within cylinder'll. Theends 'ofxicylind'erfl liarerclosedi lby; means' of..:.apertured :Itdisks 23: and 24 to receivecathode-supporting "structure, and. connecting means. for supplyingenergizing current to the-heating element:22.

E'Ihe cathode structure may besupported'by smeans .aof a concentriccathode construction l2WhlCh extends-J through longitudinal channels: 25

aandilfi infimagn'etic polepiecesell and'9;. respec- --tively. Referring-'t0'l the concentric: cable con- 'struction,:therevis provided atubular metallic miterconductor. 21, -.an..:inner conductorfi-ZB Hand aninterspaced tubular :insulatori:29. Externally aaccessible'" terminalsfOI COHdUCtOIS- ZY and 28 -'are provided..-by lead-in wires 3!). and 3 Ix which are; anchored inta g1ass.;bead-or -sea1 32. -The=.-!:seal"32-:may:. be supported by a flangedfmetallic cylinder- 33which '15 welded or soldered: to mem- 'bep Z and'-isa1so,-of course,insealed engagement 'with seal 3 2 As a means for centering and.positioningai'the concentric cathode construction,- I' employwith- 'inthevicinity-of the po'le face of pole pieces 8 an insulator 34 whichfirmly engages outer: conductor il and which is also'in'cngagement with-"'the- -wall-of channel 25. LInsulator 34 maybepo- 'sition'edlongitudinally within :channel 525 ii-by means of acopper tube- '35whichabuts v the=upper endof in'sulator :34. 'At the lower sextremr'ity;the cathode structure rmayi-becsupported and "centered by means of an 5additional insulator 36 within channel 26,. and. is sprovldedcwith-z-aitcentering: pin" 31 which extends through: there aperture in disk 24 andis turned over, thereb forming a firm lower support for the cathode.

It will be noted that the upper terminal of the cathode heatin element22 is connected to the 5 inner conductor 28, and that the lower terminalis connected to the disk 24, thereby completing the energizing circuitfor the heating elenmentzthrough cjzlinderZl, fdi'Sk 23and outer con--ductor Z'l.

Certain features of the concentric cathode "construction and theinsulating support therefor .are: disclosed and claimed in my copendingpatent application Serial No. 465,424, filed November 13, :1942 and nowUnited States Patent No. 2,406,277, issued August 20, 1946, and in acopending patentapplication of George M. White, Serial.No..465. l-01,.also filed November 13, 1942 and now United States Patent No. 2,406,276,issued- Augr1st 20, 1946, both of which are assigned to the assignee ofthe; .present application.

'Asra'means for extracting high frequency encrgy'from the variousspace-resonant'regions, suitable output electrode means are providedwhich may take the'form ofa: loop 38comprising anextension of an innerconductor 39 constiltutingapart of a concentric transmission-lineincluding conductor and an outer tubular conductor 40.

I provide an improved coupling structure for 1 the various spaceresonant regions defined by the radial vanes shown in plan View :in Fig.2. This coupling means may comprise a single or a plurality of circularmetallic conductors whichare inelectrical contact with the vanes 1,preferably .asclose to the inner extremities thereof asmechanicalexpediency will warrant. For example, 1:. providecircular-conductors 4| and-42 lyingin .;grooves-r4 3 and-44 so as to besubstantially flush with the upper surface, or top surface, -of,theaanode. structure d.

:.Conductor@4 I: is-electrically connected to vanes la, 1e, 1e and lg,being in electrical contactwlth fthe- 'walls of ,grOOVGSHlQfiIldnot-being in contact with'the alternate .or intermediatevvanes due tothe fact that grooves 44. are of sufficient size I to permit the passageof :the conductor therethrough without contacting the intermediatevanes. Conductor 12,. on the other hand, .electrically connects vaneslb, 51d, 'lfandlh, .counotbeing in contact with the vaneslaflq'i-le andlg. 'Theplan'of coupling the vanes*1a-'-lh,,in-

elusive, mayibein accordance with that disclosed and claimedwin mycopending-patent applicaitiont-Serial No. 162,123, filedDctober 15, 1942,55 and which is assignedzto'thezassigneelofithe. present application.

1' Conductorstl and-'42 need not be continuous,

. and! the'length' thereof, or the number of vanes to @which each ofthese conductors; is connected 'n1ay be chosen torestabli'slr thedesired mode of l' Qp8Iati0I1.0f theqdischarge device-as a wholeso thatthe :operatingv frequency or [mode 'is..determinable.

lfhrdesired a similar coupling structuremay be .65: provided-.inthebottom ofthe anode structure. 'Suchuan .,arrangement is :illustrated inFig. 1 wherein additional coupling conductors -and All: are shown, lyingin grooves or slots in the bot- -:tomsplane of the anode structured.

.1An important feature I of apparatus built. :in raccordance-rwith.;my-=invention is: the increased efliciencyrobtainable by. the proper:dimensioning of lthewradialwvane-thicknessvwith respect to the spacingtherebetweenzat the region immediately 1 opposite the: cathode wherebythere. is; an effective concentration of the electric field incident tothe electromagnetic fields within the respective space resonant regions.In this manner there is provided eificient transmission of energy fromthe oscillating space discharge to the space resonant regions.

Another important advantage is the provision of the coupling means atthe extremities of the radial vanes, which positioning accomplishes mostefiective coupling of the various regions. One of the desirable objectsof any coupling means in a device of this type, of course, is thefrequency selection or the mode of operation at which it is desired tooperate the device as a whole. With the coupling means at the innerextremities of the radial vane T, I have found that the frequencyselection or mode of operation is highly discriminatory orpredeterminable.

A further advantage of apparatus built in accordance with my inventionis the simplified construction which lends itself to factory productionmethods and apparatus. It will be readily apparent upon inspection ofthe structure that the ring 5 may be readily slotted to receive theradial vanes I and that the radial vanes may be easily inserted into theslots 6 so provided. Furthermore, as concerns the machining operationsof the groove 43 and 44 which receive the circular and flexible couplingconductors 4| and 42, the vanes I may be slotted or grooved prior toinsertion into the grooves 6, and due to the fact that the vanes arerectilinear in configuration a relatively large number of similar vanesmay be machined in one operation by placing the vanes in juxtapositionin the grooving or slotting machine.

While I have shown and described my invention as applied to a particulardevice, it will be obvious to those skilled in the art that changes andmodifications may be made without departing from my invention, and I,therefore, aim in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electric discharge device of the magnetron type comprising anenvelope, a plurality of electrodes within said envelope including acathode and an open-ended cylindrical anode structure surrounding saidcathode, said anode structure comprising an annular ring portion and aplurality of vanes extending radially inwardly from said cylindricalportion, the inner ends of said vanes and said cathode bounding asubstantially annular interelectrode space, means coupling together thecavity resonators defined by said vanes, said means comprising on eachend of said anode structure a pair of annular metallic rings near theends of said vanes facing said cathode, one of said rings in each ofsaid pair being electrically connected to alternate vanes, the other ofsaid rings in each said pair being electrically connected to the vanesintermediate between said alternate vanes.

2. A device as in claim 1 including within said envelope magneticmembers adjacent the opposite ends of said anode structure forestablishing a magnetic field in the region between said cathode andsaid anode structure.

3. An electric discharge device of the magnetron type comprising anenvelope, a plurality of electrodes Within said envelope including acathode and an open-ended cylindrical anode structure surrounding saidcathode, said anode structure comprising an open-ended metallic cylinderand a plurality of vanes extending radially inwardly from said cylinder,said vanes having uniform thickness substantially greater than thedistances between adjacent vanes at their inner extremities, the ends ofsaid vanes and said cathode bounding an annular interelectrode space,means coupling together the cavity resonators defined by said vanes,said means comprising on each end of said anode structure a pair ofconcentric annular metallic rings positioned within grooves in saidvanes near the ends of said vanes facing said cathode, one of said ringsin each of said pair being electrically connected to alternate vanes,the other of said rings in each said pair being electrically connectedto the vanes intermediate between said alternate vanes.

4. A device as in claim 3 including within said envelope magneticmembers adjacent the opposite ends of said anode structure forestablishing a magnetic field in the region between said cathode andsaid anode structure.

RALPH J. BONDLEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,063,342 Samuel Dec. 8, 19362,147,159 Gutton et al Feb. 14, 1939 2,187,149 Fritz Jan. 16, 19402,247,077 Blewett et al June 24, 1941 2,259,690 Hansen et a1 Oct. 21,1941 2,305,781 Helbig Dec. 22, 1942 2,309,966 Litton Feb. 2, 19432,408,235 Spencer Sept. 24, 1946 2,417,789 Spencer Mar. 18, 1947 FOREIGNPATENTS Number Country Date 215,600 Switzerland Oct. 16, 1941 509,102Great Britain July 11, 1939

